Successful rail mounting assemblies are disclosed in U.S. Pat. No. 6,789,740 and to U.S. patent application Ser. No. 10/691,454 (now U.S. Pat. No. 6,986,470). In these rail mounting assemblies which can be referred to as “egg” designs, the frame has a generally elongated or oval opening formed at its ends with inclined faces and four lugs symmetrically disposed at opposite ends of the frame to receive bolts for attachment of the base plate to the support structure.
The top plate is also symmetrical about the longitudinal axis and has at its ends inclined faces juxtaposed with the inclined faces of the frame and bonded, e.g. by vulcanization, to an elastomer body received between the juxtaposed faces and extending around the sides of the top plate and the frame. Such track fasteners are particularly useful for vibration-sensitive locations.